Infusing bag containing combination of dried extract and ligneous adsorbent and process of preparing same

ABSTRACT

An aqueous extract of a vegetable material is treated with a view to reducing its caffeine and/or chlorogenic acid content. The treatment is with a solid ligneous adsorbent of vegetable origin in divided form at a temperature of from 0° to 100° C. so as to absorb the caffeine and the chlorogenic acid. The combination of extract and ligneous adsorbent is dried by freeze-drying. The dried combination is thereafter introduced into infusing bags. On infusing the bags in hot water, an extract is obtained in partially decaffeinated and partially deacidified form.

This is a division of application Ser. No. 842,987, filed Oct. 17, 1977and now U.S. Pat. No. 4,160,042.

BACKGROUND OF THE INVENTION

This invention relates to the treatment of vegetable materials with aview to reducing the content of certain undesirable substances,particularly caffeine and chlorogenic acid.

For some time now, efforts have been made to find an industrial methodfor decaffeinating vegetable materials, particularly coffee, which doesnot involve the use of organic solvents. The techniques currently usedin industry for decaffeination use organic solvents, such astrichlorethylene, methylene, chloride, chloroform, etc., the caffeinebeing extracted by contacting the vegetable material itself or anextract thereof with these solvents which, laden with caffeine, have tobe subsequently separated.

These solvent extraction techniques are attended by numerousdisadvantages. The operational burden associated with the treatment andrecycling of these solvents is considerable. Being volatile and toxic,they necessitate expensive safety measures and have to be carefullyeliminated from the beverage. Finally, they solubilise non-selectively acertain number of desired constituents of the beverage which often hasto be isolated and reincorporated in the product after decaffeination.

In order to eliminate these disadvantages, several attempts have beenmade to effect decaffeination by other means.

For example, French Pat. No. 698,118 describes the use of active carbonor silica for eliminating the caffeine and other undesirable elementsfrom an aqueous extract. However, other interesting soluble constituentsof the coffee are also adsorbed and the difficult regeneration of theadsorbent cannot be carried out on an industrial scale.

According to U.S. Pat. No. 3,108,876, a coffee liquor may bedecaffeinated by using ion exchange resins. The disadvantage of thismethod is the simultaneous adsorption of other interesting constituents,the demineralisation and the reduction in pH of the liquor. The liquorhas to be subsequently neutralised to increase its pH-value to anacceptable level and to restore the mineral substances.

Published French Patent Application No. 2,297,004 relates to a processfor decaffeinating an aqueous extract of a vegetable material byadsorption on neutral polymer resins. The disadvantage of this method isthat, in addition to the caffeine, it adsorbs certain interestingsoluble constituents of which the recovery necessitates treatment with awater/alcohol mixture, followed by subsequent washing of the resin.

Another process, which is described in published French PatentApplication No. 2,231,407, sets out to fix a substance to be separatedfrom an aqueous medium, for example caffeine, on a macromolecularsubstance in the liquid state and subsequently to separate the aggregateformed by ultra-filtration on a semi-permeable membrane. However, thismethod has not so far been accepted for industrial application.

SUMMARY OF THE INVENTION

The present invention relates to a process for treating an aqueousextract of a vegetable material on an industrial scale which does notinvolve the use of solvents, is simple to carry out and does not haveany of the disadvantages of conventional processes.

In the following description, the expression "aqueous extract of avegetable material" applies to any vegetable material containingcaffeine, such as coffee, tea, cola, mate, guarana, etc.

It is preferred to treat an aqueous extract of tea or unroasted orroasted coffee and, more particularly, an aqueous extract of roasted andground coffee.

The term "deacidification" applies specifically to the removal ofchlorogenic acid.

The term "treatment" applies either to decaffeination anddeacidification together or to deacidification alone, for example in thecase of coffee, or even to decaffeination alone, for example in the caseof tea which does not contain any chlorogenic acid.

The process according to the invention is characterised in that theaqueous extract is contacted with a solid ligneous adsorbent ofvegetable origin in finely divided form at a temperature of from 0° to100° C. so as to adsorb the caffeine and the chlorogenic acid.

DETAILED DESCRIPTION OF THE INVENTION

The adsorbent substance used has a power of adsorption which is highlyspecific to caffeine and chlorogenic acid. The treatment does not removesignificant quantities of the other soluble constituents present in theextracts. This is an unexpected and decisive advantage of the processaccording to the invention because chlorogenic acid is partlyresponsible for the acidity of coffee extracts for example and thegastric acidity which it produces is not appreciated among certaingroups of consumers. Accordingly, efforts have long been made to sweetenthis beverage. It is possible by virtue of the process according to theinvention, depending upon the way in which it is carried out, to effectdecaffeination and simultaneously to remove the chlorogenic acid tovarious levels, which gives a remarkable degree of flexibility foradapting the flavour and aroma of the beverage to different tastes.Thus, it is possible to obtain different levels of decaffeinationranging up to 97% and to remove approximately 60% of the chlorogenicacid present.

It has been found that, in the process according to the invention, theadsorbent laden with caffeine and chlorogenic acid may readily beregenerated, simple lixiviation with hot water enabling most of thecaffeine and some of the chlorogenic acid adsorbed to be eluted, afterwhich the adsorbent may be used for a new cycle. This regeneration maybe carried out a large number of times without any significant reductionin the power of adsorption of the adsorbent.

In addition, it has been found that there is no need for the adsorbentto be completely regenerated to obtain satisfactory adsorption in thefollowing cycle.

On the other hand, it has surprisingly been found that, although itenables almost all the caffeine to be desorbed from the support,lixiviation with hot water does not result in total desorption of thefixed chlorogenic acid, adsorption of almost 45% of the chlorogenic acidon the support appearing to be irreversible under the temperatureconditions of the lixiviation treatment. This interesting phenomenon maybe utilised to produce a deacidified, but essentially non-decaffeinatedextract.

Accordingly, if it is desired to produce a deacidified extractcontaining most of the caffeine of the extract before treatment, thelixiviation waters will be reincorporated in the treated extract whichwill then be subjected to the subsequent operations leading to a solublecoffee powder. On the other hand, it is possible to carry out thetreatment directly at a temperature above 60° C., for example at atemperature of 95° C., and thus to obtain an essentiallynon-decaffeinated extract having a greatly reduced chlorogenic acidcontent, for example with elimination of approximately 40% of theinitial chlorogenic acid.

Finally, it has been found that the beverage obtained by carrying outthe process according to the invention is organoleptically equivalent orsuperior to a beverage obtained from an untreated soluble coffeeextract. It may be concluded from this that the treatment does not haveany adverse effect upon the intensity or equilibrium of the aromas.

One possible explanation for this phenomenon might be the formation ofcomplexes between the caffeine, the chlorogenic acid and the support.

In particular, it may be assumed that adsorption is subjected to anequilibrium similar to complex formation. It is promoted by a reductionin temperature, an increase in temperature resulting in dissociationand, hence, in desorption.

The solid ligneous substances which may be used in the process accordingto the invention may vary widely in their nature. They are solid fibrousparticles obtained by the coarse grinding of parts of vegetables rich inlignin such as the pulps, husks, shells, pods of fruits or vegetables orthe peels. One particularly suitable material which is available inlarge quantities is constituted by the fibrous residues emanating fromcarob pods from which the sugars are extracted with hot water. The carobor locust tree, Ceratonia siliqua (a member of the Leguminosae family),is a tree which can grow to a height of 20 meters which was originallyfound in Syria but which is now widely cultivated in the Mediterraneancountries. Its fruit contains seeds of which the endosperm is the sourceof carob gum. The pericarp or pod is either discarded or used to producea low-quality syrup (carob syrup) or even in animal fodder. The residuesare normally discarded.

Thus, the starting material used for producing the adsorbent consistseither of pods or of residues emanating from the extraction of sugars.It is therefore of advantage to treat this material by any suitablemethod to free it from impurities, sugars and carob aromas. Normally,the material is subjected to coarse grinding. In cases where thenondesugared pods are treated, one convenient method consists in coolingthem for example to -40° C. and grinding them. The particles of carobpods or partially desugared residues are subjected to a treatment withhot water to eliminate the sugars. It is possible for example to use abattery of in-line extraction cells and to extract the sugars with hotwater, for example at 95° C. The carob particles are then advantageouslydried, for example under a light vacuum, which enables them to bedeodorised.

On the other hand, these particles may be treated with an acid andsubsequently subjected to stripping with steam. It has been found that,in the case of this material, the acid treatment does not affect itsadsorption capacity for caffeine and chlorogenic acid, but greatlyfacilitates subsequent deodorisation. For this treatment, it is possibleto use any suitable acid such as, for example, hydrochloric acid,sulphuric acid or phosphoric acid in diluted or concentrated form.

A treatment with dilute hydrochloric acid for 1 to 3 hours at ambienttemperature is suitable. For practical reasons, it is preferred to use amaterial having fairly uniform granulometry. The material is thensieved, the retained particles advantageously having grain sizes of from0.3 to 5 mm and preferably from 0.5 to 4 mm.

The aqueous extract of the vegetable material to be treated may containfrom 1 to 50% and preferably from 12 to 25% by weight of solubleconstituents. It may have been freed beforehand from volatile aromas bystripping or distillation with steam, for example in countercurrent, thearomas being collected for reintroduction at a subsequent stage of theprocess.

Although it is not necessary to strip the aromas before the treatment,it is preferable to do so if the final beverage is to retain its flavourand aroma.

The volume of extract treated per unit of weight of adsorbent used (Vr)is advantageously from 6 to 80.

The actual treatment may be carried out by any method which provides forgood solid/liquid contact between the adsorbent and the extract.

It may be carried out for example in the stationary phase or underdynamic conditions.

In one embodiment carried out in the stationary phase, the extract to betreated is passed through a container, for example a column, lined witha bed of adsorbent, preferably saturated with water.

A Vr from 6 to 10 is advantageously used.

As mentioned above, adsorption is promoted by low temperatures. However,when the temperature is too low, the adsorption rate is also too low,with the result that the period of time required to reach theequilibrium is too long.

It has been found that absorption takes place under good conditions attemperatures of from 10° to 30° C. and is preferably carried out atambient temperature.

Adsorption may be carried out in batches, the flow of the extractthrough the bed being interrupted when the activity of the adsorbent issubstantially reduced as a result of its saturation with caffeine andchlorogenic acid.

The adsorbent is then washed either once or, better still, several timeswith water at a temperature of from 0° to 30° C. and preferably atambient temperature. By virtue of this operation, it is possible toremove from the bed the soluble constituents other than the caffeine andthe chlorogenic acid which have not been adsorbed and thus to increasethe content of soluble constituents in the extract. These washing watersmay be combined with the initial extract or may be used for extractionor, preferably, may even be added to the treated extract.

The adsorbent is then lixiviated with hot water at a temperature above60° C. and preferably at a temperature of from 80° to 100° C. so as todesorb the caffeine and the chlorogenic acid and to regenerate theadsorbent.

This operation may also be carried out at a temperature above 100° C.,for example at 105° C. under pressure, on the condition that it does notdeteriorate the particles of adsorbent. During this operation, almostall the caffeine and some of the chlorogenic acid are eluted and theregenerated bed may be used for a new treatment. In a variant, thisliquid-solid extraction may be carried out over a period of 1 hour withrecirculation of the steam in accordance with the principle of theSoxhlet apparatus.

The volume of the cold and hot washing waters is advantageously from 1to 4 times the volume of the treated extract.

In order to obtain a decaffeination level of 97% and a deacidificationlevel of 60%, a cyclic procedure is adopted. To this end, the extract ispassed through the bed of adsorbent and approximately half the volume ofthe initial extract is subsequently collected and separated. The rest ispassed through the bed, the adsorbent is washed first with cold waterand then with hot water, as indicated above, the washing waters and thesecond half of the extract are combined and the whole is concentrated toapproximately half its volume. This concentrated solution is then passedthrough the bed of adsorbent and the preceding operations are repeated.

In a variant, a continuous procedure may be adopted using several bedspreferably arranged in series.

When the extract is passed through any one of the beds or through aseries of beds, other exhausted beds may be isolated from the circuitand regenerated in the meantime, which provides for continuousoperation. Thus, by arranging several beds in series so that the extractcomes successively into contact with less exhausted beds, it is possibleto obtain maximal removal of the caffeine and chlorogenic acid. Forexample, under the same principle as continuous extraction with abattery of extraction cells, when the first bed of the series iscompletely exhausted, the cell may be isolated from the circuit andregeneration of the bed may commence. On the other hand, a cellcontaining a regenerated bed may simultaneously be connected to form thelast cell of the circuit, which guarantees effective, relatively uniformdecaffeination and deacidification.

For regenerating a bed, the operations of washing with cold water andlixiviation with hot water are carried out as indicated above.

In another embodiment of the process according to the invention which iscarried out under dynamic conditions, the adsorbent, preferablysaturated with water, is suspended in the extract and the suspensionobtained is stirred for 15 to 180 minutes at 10° to 150° C. andpreferably at ambient temperature.

The quantity Vr is advantageously from 10 to 80. It has been found thatthere is a linear relation between the percentage decaffeination leveland the quantity Vr for 2 hours of contact and also between thepercentage deacidification level and the Vr for an extract having agiven solids content. Thus, for low values of Vr, at which effectivecontact is difficult on account of agitation difficulties, the advantageof a greater adsorption capacity is cancelled out by the disadvantage ofpoorer transport or a lower molecular mobility of the caffeine and thechlorogenic acid. On the other hand, the adsorption equilibrium is notreached after 2 hours in the case of an excessively high value of Vr.

When the solids content increases for a given value of Vr, thedecaffeination and deacidification levels increase, although agitationdifficulties are encountered when the solids content reaches 50%. Thus,it has been found that, for extracts having solids contents of 13%, thepreferred value of Vr is 40:1, because it leads to decaffeination levelsof 40 to 50% in 2 hours, the equilibrium being reached between 90 and120 minutes and effective agitation being possible.

The intensity of agitation should be sufficient to provide for goodcontact between the adsorbent and the extract. When the adsorptionequilibrium is reached, the treated extract is separated from theadsorbent by centrifuging or filtration. As in the case of operation inthe stationary phase, the adsorbent is subsequently washed once orseveral times at a temperature of from 0° to 30° C. These washingoperations with cold water have to be carried out rapidly (the contacttime being of the order of 10 to 30 seconds), as does the subsequentfiltration step so as to desorb the minimum of caffeine and chlorogenicacid. As mentioned above, the washing waters are preferably combinedwith the decaffeinated extract. Desorption may be carried out in one orseveral stages by lixiviation with hot water, preferably at atemperature of from 80 to 100° C., for example at 90° C., with goodagitation for at least 15 minutes and, advantageously, for 1 hour. In avariant, it is possible to carry out an extraction at 100° C. withrecirculation of the steam in an extraction of the Soxhlet type. Thevolume of the hot and cold washing waters is with advantagesubstantially equal to the volume of treated liquor. Although it ispossible to use the adsorbent once only and to use a new batch ofadsorbent for each new batch of extract, it is normally preferred toadopt a cyclic procedure using the same batch of adsorbent several timesfor treating successive batches of extract and regenerating theadsorbent between each adsorption phase.

It is thus possible to obtain a final extract decaffeinated to a levelof from 20 to 60% and deacidified to a level of from 10 to 55%.

For this embodiment, it is preferred to adopt a semi-continuousprocedure, for example by using several containers in which theadsorption phase is carried out whilst the adsorbent is regenerated inother containers.

When the equilibrium is reached, the suspension may be directed to awashing-type centrifuge for separating the extract from the adsorbent.Regeneration is then carried out, the phases of washing with cold waterand lixiviation with hot water being carried out for example in thecentrifuge. The regenerated adsorbent may then be transferred to acontainer for treating a new batch of extract.

In a variant, it is possible to use an apparatus comprising anadsorption chamber containing the suspension provided with means for theagitation, filtration and rapid transfer of the liquids, for example bymeans of vacuum or compressed air, from the adsorption chamber tocollecting vessels and means for condensing and circulating steamthrough the bed of adsorbent to effect the Soxhlet-type lixiviation in aclosed circuit. In another suitable apparatus, the adsorption chambercomprises a fixed container, into which the extract to be treated isintroduced, and a mobile part acting as agitation means and comprisingat least one chamber in which the adsorbent is placed and of which thewalls are such that they allow the extract to pass through withoutdifficulty, but retain the adsorbent. One example of a mobile part suchas this comprises several spheres of perforated metal or metallicnetting mounted on a shaft at a certain distance therefrom and in aplane perpendicular to its axis similarly to the blade of an agitator.The whole may be rotated in one direction only or alternately in onedirection and then the other. For the displacement of the extract fromthe adsorbent by rapid washing with cold water, it is possible toprovide a hollow shaft through which the water arrives directly insidethe spheres, subsequent removal of the washing waters being obtainableby rapidly rotating the shaft.

Irrespective of the method of treatment adopted, i.e. treatment in thestationary phase or treatment under dynamic conditions, it is desirablefor the extract to have a solids content of from 30 to 60% by weight andpreferably from 40 to 50% by weight to effect drying. The cold washingwaters (in the case of simultaneous decaffeination and deacidification)or the hot lixiviation waters (in cases where it is desired to obtain adeacidified, but essentially non-decaffeinated beverage) are normallycombined with the decaffeinated extract which reduces the solids contentthereof. Accordingly, it is often necessary to concentrate the extractbefore it is dried by any known method, for example by evaporation invacuo. The concentration treatment may be carried out downstream of thedecaffeination process or, where the extract is repeatedly passedthrough a bed of adsorbent, preferably between each passage. However,the extract must be prevented from being too viscous because this wouldmake the adsorption operation too long or would lead to inadequatecontact between the liquid and the adsorbent as a result of thedifficulty of obtaining suitable agitation.

In practice, a solids content of 60% represents the upper limit evisagedfor operation under dynamic conditions.

The decaffeinated and concentrated extract may be dried by anyconventional method, such as freeze-drying or spray-drying. In addition,it is desirable to reincorporate in the dried product the volatilematerials responsible for aroma and flavour which were removed duringthe decaffeination treatment. To this end, it is possible to use anyknown method of contacting or, alternatively, to return the volatilematerials towards the concentrated extract.

If it is desired to recover the caffeine from the waters emanating fromthe lixiviation with hot water, it is possible for example to free thesewaters from the chlorogenic acid by passage over an ion exchange resinand to crystallise the caffeine by cooling. Alternatively, the caffeinemay be separated from the lixiviation waters by means of a systemcomprising a membrane for reverse osmosis.

According to the invention, it is entirely possible to use any methodwhich provides for good contact between the adsorbent and the extractand which leads to the required decaffeination and deacidificationlevels. Thus, it is possible to treat an extract in suspension, asdescribed above, to dry the whole formed by the adsorbent and thetreated extract without separating the adsorbent, for example by freezedrying, and to package the dry product obtained in a bag ready for use,for example of cloth or paper, the decaffeinated beverage then beingdirectly obtained by soaking the bag in a coffee maker or in a cup. Itis also possible to envisage for example a domestic coffee makerprovided with a filter containing the adsorbent arranged in such a waythat the extract has to pass through it.

EXAMPLES OF THE INVENTION

The following non-limiting Examples show how the invention may becarried into effect. The percentages and parts quoted in the Examplesare by weight, unless otherwise indicated.

Example 1

(A) Production of the adsorbent

10 kg of residues of carob pods emanating from extraction of the sugarsare ground to a particle size of less than 2 mm. This batch is placed ina tank containing 50 kg of deionised water at 60° C. and stirred for 30minutes at the same temperature.

The solids are separated, stirred for 30 minutes at 60° C. with 50 kg ofdeionised water and then separated again. 25 liters of 2 N hydrochloricacid are then added, followed by stirring for 2 to 3 hours at 20° C. Thesolids are separated and washed with dionised water until the washingwaters are colourless. The solids are then separated again anddeodorised by stripping with steam under a light vacuum (50 mm Hg, 100°C.) for 2 to 3 hours. After separation, the carob particles are driedand sifted through a 0.3 mm mesh screen. Particles with grain sizes offrom 0.3 to 2 mm are thus collected. The hydrochloric acid used for thepreceding treatment may be replaced by sulphuric acid or phosphoric acid(2 N) with similar results.

(B) Relative adsorption of the caffeine and chlorogenic acid insuspension

Aqueous solutions respectively containing 1 mg/ml of caffeine (solutionI), 1 mg/ml of chlorogenic acid (solution II) and 1 mg/ml ofequimolecular caffeine/chlorogenic acid complex (solution III) areprepared.

The adsorbent is suspended in a quantity of 1 g of adsorbent for 40 mlof solution and the suspension is stirred. Measurement of the quantitiesof caffeine and chlorogenic acid adsorbed as a function of time byUV-spectrophotometry (the caffeine at a wavelength of 272 mμ, extinctionE=15400 l/m and the chlorogenic acid at 320 mμ, E=17030 l/m) producedthe results set out in Table 1 below:

                  TABLE 1                                                         ______________________________________                                                  % caffeine and/or chlorogenic acid (c.a.)                                     adsorbed after X hours                                              Solution           1/4     1/2   41/2   24                                    ______________________________________                                        I                  25      30    37.5   44                                    II                  3       6    7      16                                    III         caf-   21      22    30     31                                                feine                                                                         c.a.    3       3    6      14                                    ______________________________________                                    

It is found that the relative quantity of caffeine adsorbed in the caseof a solution of pure caffeine is greater than that adsorbed from asolution of the caffeine/chlorogenic acid complex. The same observationmay be made for the chlorogenic acid. It is also observed that theaffinity of the adsorbent for caffeine is 2 to 3 times greater than itsaffinity for chlorogenic acid.

If the preceding test is repeated with coffee liquors having solidscontents of 13% with, respectively, an adsorbent which has not beentreated with acid, a second adsorbent which has been treated with 2 Nhydrochloric acid and a third adsorbent which has been treated with 2 Nphosphoric acid, caffeine fixing levels of 38%, 37% and 38% are obtainedafter 24 hours as against corresponding levels of 34%, 31% and 31%,respectively, for chlorogenic acid. Accordingly, it can be seen that theacid treatment has virtually no effect upon the adsorption properties inthe case of carob. By contrast, this treatment provides for effectivedeodorisation of the adsorbent.

Example 2

In this Example, the coffee liquors to be treated are subjected tocentrifuging to eliminate the solids remaining in suspension. They havea solids content of 13%, unless otherwise indicated.

The various tests are carried out using a column with a double jacketfor the circulation of water, enabling the column to be operated atdifferent temperatures. This column is provided at its base with afilter and a cock enabling different fractions to be collected. It isfilled with adsorbent saturated with water.

The treatment comprises an adsorption phase at ambient temperature,during which the liquors are passed through the column, followed by adesorption phase either at ambient temperature or at elevatedtemperature, during which the column is washed either with cold water orwith hot water. The adsorbent may also be subjected to an extraction at100° C. in a Soxhlet apparatus.

The spectrophotometric determination of the caffeine and chlorogenicacid (c.a.) contents in the coffee liquors cannot be carried out in thesame way as for the standard solutions due to the interference of theother constituents of the coffee. Thin-layer chromatography is usedinstead. The solvent system CH Cl₃ :CCl₄ :CH₃ OH in proportions of 5:5:1separates the caffeine (RfΩ0.45) measured with a Zeiss densitometer at272 mμ.

The solvent system eluting the chlorogenic acid consists of CH₃ COOC₂ H₅:H₂ O:C₂ H₅ OH:CH₃ COOH in proportions of 6:2:2:0.2 (RfΩ0.55) measuredwith a Zeiss densitometer at 320 mμ.

The final estimation is made in relation to adsorption levels measuredfor standard solutions of caffeine and chlorogenic acid of knownconcentration.

I. 400 ml of coffee liquor are passed through a column containing 50 gof adsorbent (200 ml). Four fractions of 100 ml each (F1-F4) arecollected. In the desorption phase, the adsorbent is washed with 200 mlof water at ambient temperature in order to flush out thenon-specifically associated solids (F5), after which the 50 g ofadsorbent are extracted for 1 hour with 750 ml of water at 100° C. in aSoxhlet apparatus (F6).

The total solids content and percentage of caffeine eluted in thevarious phases are shown in Table 2 below:

                  TABLE 2                                                         ______________________________________                                                                    % of total solids                                 Fraction                                                                             Total % of caffeine eluted                                                                         collected                                         ______________________________________                                        1      0                                                                      2                  3                                                          3                          12                                                 4                                    24         71                            5      30                                       16                            6      45                                       12                            ______________________________________                                    

It is found that fractions 1 and 2, representing 50% of the liquor, havebeen almost completely decaffeinated (to a level of 97%) and that thepassage of all the liquor and washing with cold water enable 87% of thesolids to be collected.

II. The procedure is as in paragraph I above using a column containing 5g of adsorbent for treating 30 ml of coffee liquor, with the differencethat a larger number of elution fractions is collected, namely threefractions of 10 ml (F1-F3), two fractions of 10 ml (F4-F5) emanatingfrom the wash at ambient temperature, three fractions of 10 ml each(F6-F8) emanating from a lixiviation at 90° C. and, finally, twofractions of 30 ml each obtained by Soxhlet extraction for 1 hour at100° C. (F9-F10). The cumulated percentages of caffeine, chlorogenicacid, the total solids and the colour are determined for each fractioncollected and are shown in Table 3 below.

                  TABLE 3                                                         ______________________________________                                        % cumulated                                                                                     chlorogenic                                                 Fraction                                                                              caffeine  acid       colour total solids                              ______________________________________                                        1       0         0          4      6                                         2       0         0          15     21                                        3       0         7          27     42                                        4       3         18         45     64                                        5       8         32         56     76                                        6       23        45         73     86                                        7       44        54         83     93                                        8       53        55         88     95                                        9       68        55         95     97                                        10      85        55         100    98                                        ______________________________________                                    

It is found that the caffeine is retained preferentially over thechlorogenic acid and that the solids responisble for coloration areretained preferentially over the total solids. This property may beutilised for partially decolouring the coffee liquors. 64% of the totalsolids are eluted with 3% of the total caffeine and intense washingelutes almost all the solids and the colour.

It is surprisingly found that 45% of the chlorogenic acid remains fixed.This may be utilised to produce a partially deacidified andnon-decaffeinated beverage.

III. 40 ml of coffee liquor are treated in a column containing 5 g ofabsorbent at ambient temperature. 22 ml of this liquor containing 3% ofcaffeine and 55% of total solids are eluted and placed to one side(fraction F1). The remaining 18 ml are combined with 55 ml of wateremanating from the wash at 90° C., the whole forming the fraction F2.Fraction F2 is concentrated by evaporation to 40 ml which arereintroduced into the column and the operation is repeated to give thefractions shown in Table 4 below:

                  TABLE 4                                                         ______________________________________                                                               % de-                                                  Fraction  Volume (ml)  caffeination                                                                            % solids                                     ______________________________________                                         ##STR1##    22         97        55 of the total solids                       ##STR2##  18 + 55 (waters from the 90° C. wash) evaporated to 40                 32           97        55 of the solids of F2                       ##STR3##  8 + 40 (waters from the 90° C. wash) evaporated to 25                 0             97        55 of the solids of F4                       ##STR4##                                                                               5 + 50 (washing                                                                    waters)                                                        ______________________________________                                    

Combinations of the fractions F1, F3 and F5 gives a liquor decaffeinatedto a level of 97% and containing 91% of the initial solids.

Fraction F6 contains 97% of the initial caffeine and approximately 60%of the initial chlorogenic acid.

IV. 13 aliquots each containing 600 mg of caffeine are successivelypassed through a column containing 2 g of adsorbent, the column beingwashed between each adsorption phase. Hardly any reduction in theadsorption capacity is observed after 13 cycles.

V. Aliquots of 40 ml of coffee liquor having a solids content of 20% andcontaining 280 mg of caffeine are successively passed through a columncontaining 4 g of adsorbent. Adsorption is carried out at ambienttemperature and the desorption between each adsorption phase with 90 mlof water at 90° C.

The quantities of caffeine fixed and eluted are shown in Table 5 below:

                  TABLE 5                                                         ______________________________________                                                 Caffeine  Caffeine           Caffeine                                         introduced                                                                              fixed    %         cluted                                  Passage No.                                                                            (mg)      (mg)     decaffeination                                                                          (mg)                                    ______________________________________                                        1        280       253      90        222                                     2        280       242      87        194                                     3        280       248      88        148                                     4        280       242      87        202                                     ______________________________________                                    

The preceding tests show that it is possible to treat the liquorscontaining 13% of solids and to obtain a decaffeination level of 97%with a recovery of 91% of the total solids. On the other hand, the samebatch of adsorbent may be used several times without any significantchange in its adsorbent properties when it is regenerated between eachadsorption cycle.

EXAMPLE 3

I. In a container equipped with an agitator, 1 g of adsorbent (grainsize distribution 0.5-2 mm) is suspended in 40 ml of coffee liquorhaving a solids content of 13%, and the resulting suspension is stirred.

A new batch of adsorbent is used for each test. After a certain time,the caffeine and chlorogenic acid contents of the liquor are measured.The results obtained are set out in Table 6 below.

                                      TABLE 6                                     __________________________________________________________________________                        Caffeine and chlorogenic acid (c.a)                                Weight of                                                                           Duration                                                                             Initial                                                                              Final                                            Test                                                                             Volume of                                                                           adsorbent                                                                           of test                                                                              conc.  conc.                                            No.                                                                              liquor (ml)                                                                         (g)   (mins) (mg/ml)                                                                              (mg/ml)                                                                            % decaffeination                                                                       % deacidification                  __________________________________________________________________________    1  500   12.5  60     3.95   2.25 43       40                                                       c.a 15.6                                                                             c.a 9.4                                          2  500   12.5  60     3.70   2.10 43       40                                                       c.a 15.0                                                                             c.a 9.2                                          3   40   1.0   120    3.5    1.75 50       34                                                       c.a 12.0                                                                             c.a 7.9                                          4   50   1.25  120    3.8    2.25 42       49                                                       c.a 15.5                                                                             c.a 7.9                                          __________________________________________________________________________

In the absence of stirring, only 4% of the caffeine and 3.5% of thechlorogenic acid are adsorbed after 2 hours. This demonstrates theimportance of good agitation in producing quasi-homogeneous conditions.

II. The procedure is as in I above using coffee liquors having differentsolids content and variable ratios of volume of liquor to weight ofadsorbent, the adsorbent used having a grain size distribution of from0.5 to 2 mm. In each test, 100 ml of liquor are treated for 2 hours atambient temperature. The percentage decaffeination levels obtained areshown in Table 7 below.

                  TABLE 7                                                         ______________________________________                                                       Weight of Adsorbent:                                           Test   Solids  adsorbent coffee                                               No.    content (g)       solids  % decaffeination                             ______________________________________                                        1      12      2.5       1:5     20                                           2      24      5.0       1:5     36                                           3      36      7.5       1:5     41                                           4      48      10.0      1:5     53                                           5      24      2.5        1:10   22                                           6      36      2.5        1:15   38                                           7      48      2.5        1:20   40                                           ______________________________________                                    

III. The procedure is as in I above using different adsorbent: liquorratios and adsorbents having different grain size distributions. Theresults obtained are shown in Table 8 below.

                                      TABLE 8                                     __________________________________________________________________________                           Coffee                                                          Volume        solids/                                                                           Initial                                                                            Initial                                       Weight of                                                                              of   Solids                                                                            Liquors/                                                                           absorb-                                                                           caffeine                                                                           c.a. % ad-                                    adsorbent                                                                              liquors                                                                            content                                                                           adsorbent                                                                          ent conc.                                                                              conc.                                                                              sorbed                                                                             Duration (mins)                     Test                                                                             (g)   (ml) (%) (ml/g)                                                                             (g/g)                                                                             (mg/ml)                                                                            (mg/ml)                                                                            of   5 10                                                                              30                                                                              60                                                                              90                                                                              120                       __________________________________________________________________________    A  5     50   10  10   1   3.0  9.6  caffeine                                                                           --                                                                              --                                                                              40                                                                              53                                                                              55                                                                              57                                                             c.a. --                                                                              --                                                                               6                                                                              13                                                                              42                                                                              54                        B  5     40   13   8   1   3.5  12.0 caffeine                                                                           --                                                                              --                                                                              46                                                                              51                                                                              54                                                                              57                                                             c.a. --                                                                              --                                                                              44                                                                              47                                                                              50                                                                              55                        C  1     40   13  40   5   3.5  12.0 caffeine                                                                           --                                                                              --                                                                              25                                                                              39                                                                              50                                                                              50                                                             c.a. --                                                                              --                                                                              17                                                                              23                                                                              33                                                                              38                        D  0.5   40   13  80   10  3.5  12.0 caffeine                                                                           --                                                                              --                                                                              11                                                                              15                                                                              20                                                                              30                                                             c.a. --                                                                              --                                                                              23                                                                              30                                                                              33                                                                              37                        E  0.8   40   16  50   8   3.5  14.1 caffeine                                                                            5                                                                               7                                                                              15                                                                              17                                                                              21                                                                              33                                                             c.a.  1                                                                               2                                                                               9                                                                              14                                                                              19                                                                              21                        F  2.3   50   16  20   3.3 3.5  14.1 caffeine                                                                           13                                                                              18                                                                              23                                                                              33                                                                              37                                                                              52                                                             c.a.  6                                                                              12                                                                              19                                                                              20                                                                              28                                                                              32                        G  5     50   16  10   1.6 3.5  14.1 caffeine                                                                           11                                                                              18                                                                              32                                                                              36                                                                              47                                                                              55                                                             c.a.  3                                                                               6                                                                              18                                                                              23                                                                              29                                                                              34                        H  1.6   100  13  60   8   3.2  16.0 caffeine                                                                           10                                                                              13                                                                              24                                                                              30                                                                              36                                                                              43                                                             c.a. 10                                                                              17                                                                              31                                                                              34                                                                              35                                                                              35                        I  2.5   100  13  40   5   3.2  16.0 caffeine                                                                           12                                                                              14                                                                              18                                                                              29                                                                              38                                                                              48                                                             c.a.  4                                                                              21                                                                              36                                                                              38                                                                              42                                                                              44                        J  5     100  13  20   2.6 3.2  16.0 caffeine                                                                           14                                                                              20                                                                              32                                                                              41                                                                              45                                                                              50                                                             c.a. 10                                                                              22                                                                              34                                                                              41                                                                              45                                                                              48                        __________________________________________________________________________

Tests A-D are carried out with non-sieved adsorbent having the followinggrain size distribution:

    ______________________________________                                        Grain Size                                                                    (mm)              % of total adsorbent                                        ______________________________________                                        0.354             5                                                           0.354-0.5         9.5                                                         0.5-1             35                                                          1-2               50                                                          2                 0.5                                                         ______________________________________                                    

Tests E-J are carried out with particles having a grain sizedistribution of 0.5 to 2.0 mm. It is found that there is a substantiallylinear relationship between the percentage decaffeination level and thevolume of liquor treated per unit weight of adsorbent (Vr) after 2 hoursof contact, which may be expressed by the following equation:

% decaffeination=(60.2±1.4)-(0.34±0.4) Vr

with a linear correlation coefficient for the experimental points r² of0.91.

Similarly, there is a linear relationship between the percentagedeacidification level and the quantity Vr expressed by the followingequation:

% deacidification=(57.0±2.7)-(0.32±0.05) Vr

with a linear correlation coefficient r² of 0.80.

Table 8 clearly shows that larger quantities of adsorbent (lower Vrvalue) lead to a slight increase in the decaffeination level, whereassmaller quantities seem to extend the time required to reach theequilibrium to beyond 2 hours.

Minor differences in the decaffeination and deacidification levels areobserved when a non-sieved or sieved adsorbent is used. With anon-sieved material, the equilibrium is virtually reached after 90minutes, whereas a significant increase in the decaffeination levelbetween 90 and 120 minutes is observed in the case of the materialsieved to a grain size distribution of 0.5 to 2 mm.

IV/For carrying out the cyclic treatment of the suspended liquors, thereis used an apparatus comprising:

an adsorption chamber in which the adsorbent is accommodated and whichis provided with an agitator and, at its upper end, with a condenser, aliquor reservoir and a steam inlet opening; at its lower end, it isprovided with an outlet opening for the liquids which is closed by afilter;

an intermediate container connected to the adsorption chamber by a setof multi-way cocks capable of admitting vacuum or compressed air to theadsorption chamber and to the intermediate container for carrying outthe filtration or rapid transfer of the liquids; a multi-way cockconnects the bottom of the intermediate container

either with a container for collecting the liquors and cold washingwaters,

or with a heated flask acting as collector for the hot washing watersand at the same time as a steam generator for the Soxhlet-typeextraction, extraction taking place in a closed circuit by way of a tubestarting from the upper end of the flask and delivering steam to theupper part of the adsorption chamber where the steam condenses on theadsorbent.

By way of the preceding apparatus, 100 ml of liquor having a solidscontent of 13% are agitated for 120 minutes at ambient temperature with2.5 g of adsorbent having a grain size distribution of 0.5 to 2.0 mm.The liquor is subsequently transferred and the adsorbent is rapidlywashed with 3×10 ml of water at ambient temperature with rapidfiltration. This is followed by Soxhlet extraction for 60 minutes at100° C. using 70 ml of water. The adsorbent may then be used for a newcycle. Each fraction is collected and its caffeine and chlorogenic acidcontents are measured, as are the cumulative percentages of each (%C)after each operation. The results are set out in Table 9 below.

                                      TABLE 9                                     __________________________________________________________________________    Caffeine                   Chlorogenic Acid                                                  1st                                                                              2nd                                                                              3rd             1st                                                                              2nd                                                                              3rd                                Cycle          cold                                                                             cold                                                                             cold                                                                             Hot          cold                                                                             cold                                                                             cold                                                                             Hot                             No.  Init.                                                                             Treatment                                                                           wash                                                                             wash                                                                             wash                                                                             wash                                                                             Init.                                                                             Treatment                                                                           wash                                                                             wash                                                                             wash                                                                             wash                            __________________________________________________________________________     mg/ml                                                                             3.80                                                                              2.60  0.75                                                                             0.45                                                                             0.18                                                                             0.37                                                                             15.5                                                                              10.0  4.19                                                                             2.71                                                                             0.44                                                                             0.44                            1%   100 68    2  1  1  5  100 65    3  2  1  2                               % C  0   32    30 29 28 23 0   35    32 30 29 27                              mg/ml                                                                              3.80                                                                              2.60  0.50                                                                             0.41                                                                             0.38                                                                             0.44                                                                             15.5                                                                              9.70  2.20                                                                             1.90                                                                             1.80                                                                             0.90                            2%   100 68    1  1  1  11 100 63    1  1  1  6                               % C  0   32    31 30 29 18 0   37    36 35 34 28                              a* mg/ml                                                                           3.80                                                                              2.90  0.70                                                                             0.50                                                                             0.30                                                                             0.28                                                                             15.5                                                                              11.1  5.00                                                                             4.01                                                                             0.98                                                                             0.00                            3%   100 76    2  1  1  7  100 72    3  3  1  0                               % C  0   24    22 21 20 13 0   28    25 22 21 21                              a* mg/ml                                                                           3.80                                                                              2.80  0.77                                                                             0.54                                                                             0.40                                                                             0.27                                                                             15.5                                                                              10.7  3.60                                                                             2.75                                                                             1.95                                                                             0.31                            4%   100 75    2  1  1  7  100 69    2  1  1  2                               % C  0   23    23 22 21 14 0   31    29 28 27 25                              mg/ml                                                                              3.20                                                                              2.10  1.38                                                                             0.76                                                                             0.52                                                                             0.38                                                                             16.0                                                                              9.65  3.96                                                                             2.14                                                                             1.16                                                                             0.34                            5%   100 66    4  2  2  12 100 60    2  2  1  2                               % C  0   34    30 28 26 14 0   40    38 36 35 33                              mg/ml                                                                              3.2 2.1   0.44                                                                             0.44                                                                             0.28                                                                             0.58                                                                             16.0                                                                              9.00  2.90                                                                             2.90                                                                             1.61                                                                             --                              6%   100 66    1  1  1  17 100 57    1  1  1  --                              % C  0   34    33 32 31 14 0   43    42 41 40 --                              __________________________________________________________________________     a* the treatment is carried out with a liquid having a solids content of      16%                                                                           -- not measured                                                          

The preceding Table shows that the degree of decaffeination is notreduced in relation to the initial treatment, even after 6 cycles.

It is seen that, when the cold washes are carried out rapidly, little orno caffeine and chlorogenic acid are eluted.

Table 10 below indicates the cumulative percentage of solids recoveredby the various washes.

                  TABLE 10                                                        ______________________________________                                                 Un-                                                                           treated       1st    2nd  3rd  4th                                            liquor                                                                              Liquor  wash   wash wash wash                                  ______________________________________                                        Volume     100 ml  96      10   10   10   70                                  Temperature                                                                              am-     am-     am-  am-  am-  100                                 (°C.)                                                                             bient   bient   bient                                                                              bient                                                                              bient                                    Weight                                                                        recovered (g)                                                                            13.7    12.0    0.71 0.39 0.32 0.12                                % of weight                                                                   recovered  100     88      5    3    2    1                                   Cumulative %                                                                  of solids                                                                     recovered  --      88      93   96   98   99                                  Cumulative %                                                                  decaffeination                                                                           0       32      31   30   29   18                                  ______________________________________                                    

It is found that a recovery of 10% of solids is obtained with areduction of only 3% in the decaffeination level.

Example 4

A suspended coffee liquor having a solids content of 13% is treated inaccordance with Example 1, paragraph B, respectively using the adsorbentaccording to Example 1 and the same quantity of Amberlito resin used inpublished French Patent Application No. 2,297,004, the desorption phasebeing limited to the treatments with cold water. Table 11 below showsthe percentage levels of coffee solids retained, solids lost, fixedcaffeine and fixed chlorogenic acid.

                  TABLE 11                                                        ______________________________________                                                  adsorbent according                                                           to the invention                                                                          Amberlite resin                                         ______________________________________                                        % coffee solids                                                                           10-12, of which 5                                                                           18-20, of which 5                                    retained   represent caffeine                                                                          represent caffeine                                              and chlorogenic                                                                             and chlorogenic                                                 acid          acid                                                % solids lost                                                                             <1            5.5                                                 % caffeine fixed                                                                          38            32                                                  % chlorogenic acid                                                             fixed      30            25                                                  ______________________________________                                    

Example 5

a/200 kg of a roasted and stripped coffee having a solids content ofapproximately 13% are suspended while stirring for 1 hour in 5 kg ofadsorbent, followed by centrifuging. 187 kg of a liquor having a solidscontent of approximately 12.3% are thus obtained, from which 38% of theinitial caffeine and 44% of the initial chlorogenic acid have beenremoved. The adsorbent was rapidly washed with 50 kg of cold water, butthese washing waters were not combined with the treated extract. Afterconcentration and addition of the aromatic fraction emanating fromstripping, the liquors are freeze-dried. Samples of this soluble coffeewere submitted to a panel of 8 or 14 tasters, taking as reference anuntreated extract with the same concentration to which the aromaticfreeze-dried fraction has been added.

With lightly roasted coffee, 9 of the 14 tasters considered that thetreated samples had a better flavour than the reference. None of thetasters detected any negative flavour characteristics.

With heavily roasted coffee, all the tasters were of the opinion thatthe treated samples had a fresher and hence sweeter flavour than thereference.

b/50 kg of the same liquor as before (solids content 13%, stripped) arepassed through a column containing 5 kg of adsorbent. 43% of the initialcaffeine and 45% of the initial chlorogenic acid were thus retained inthe column. 10 kg of cold washing waters essentially containing thenon-specifically associated solids are added to the treated liquor,followed by addition of the aromatic fraction, concentration and freezedrying.

Comparison of the samples with the same reference as in paragrapha/above produced the following results:

With lightly roasted coffee, 8 of the 14 tasters preferred the treatedsamples and the panel concluded in favour of the absence of any negativeeffects of the treatment on the flavour.

Example 6

The treatment of coffee liquors with the adsorbent at temperatures above60° C. lends to the selective removal of chlorogenic acid.

40 ml of coffee liquor having a solids content of 12% and containing 3.9mg/l of caffeine and 16.2 mg/l of chlorogenic acid are contacted for 15minutes while stirring with 1 g of adsorbent at 95° C., after which thetreated liquor was cooled, filtered and freeze-dried. It was found thatthe powder obtained contained 8% of caffeine and 38% of chlorogenic acidless than the initial liquor.

Example 7

200 ml of a 52% coffee liquor are contacted for 1 hour while stirring atambient temperature (22° C.) with 22 g of adsorbent. After the additionof a suitable quantity of aqueous aromatic fraction, theliquor/adsorbent mixture is freeze-dried and introduced into bags in aquantity of 1.7 g per bag.

By adding hot water to these bags, the caffeine and, in particular, thechlorogenic acid are retained preferentially over the other solids. Itwas found that, after the bags had been infused for 1 minute in water at70° C., 10% of the caffeine and 36% of the chlorogenic acid are stillretained on the adsorbent. After 3 minutes, 5% of the caffeine and 30%of the chlorogenic acid are retained. The resulting beverage has 35%less free acidity than an untreated liquor taken as reference, the freeacidity being measured by the weight in g of soda or sodium bicarbonatewhich is required to increase the pH of an infusion containing 1 g ofsolids of the coffee to pH 6.5.

Example 8

100 g of beans of unroasted Mexican coffee are blanched for 60 minutesin a current of steam at 100° C. and then infused for 30 minutes in 200ml of water at 100° C. 150 ml of the infusion, which has a solidscontent of 3.6% (i.e. contains 5.44 g of solids), are concentrated to asolids content of 13.6% and 40 ml of this concentrated liquor arestirred with 1.5 g of adsorbent for 1 hour at ambient temperature. 40%of the caffeine and 30% of the chlorogenic acid are thus adsorbed. Of5.44 g of treated solids, 5.18 g were recovered from the supernatantliquid and from 5 ml of cold washing waters of the filtered adsorbent.The remaining 260 mg which were not recovered were estimated to contain66 mg of caffeine, 120 mg of chlorogenic acid and 74 mg ofnon-specifically associated carbohydrates.

Example 9

An infusion of cold soluble tea is prepared from a hot infusion bycooling and filtration. 200 ml of this infusion having a solids contentof 2.1% and containing 0.425 mg/ml of caffeine are stirred for 2 hoursat ambient temperature with 1 g of adsorbent. After filtering andwashing the adsorbent with 20 ml of cold water, there are obtained 216ml of liquor having a solids content of 1.88% and containing 0.324 mg/mlof caffeine, which corresponds to a reduction of approximately 24% inthe caffeine content.

We claim:
 1. A process for treating an aqueous extract of a vegetablematerial to reduce its caffeine and/or chlorogenic acid content, whichcomprises contacting said aqueous extract containing caffeine and/orchlorogenic acid with a solid ligneous adsorbent of vegetable origin individed form at a temperature of from 0° to 100° C. so as to adsorbcaffeine and chlorogenic acid by suspending said adsorbent in saidextract with stirring, drying the suspension without separation of theadsorbent by freeze-drying, introducing the dry mixture obtained intoinfusing bags wherein the extract is obtained in partially decaffeinatedand partially deacidified form by infusing the bags in hot water.
 2. Aprocess according to claim 1, wherein said vegetable material is coffee.3. A process according to claim 1, wherein said adsorbent is formed byparticles of carob pods.
 4. A process according to claim 3, in whichsaid particles of adsorbent are obtained by desugaring, deodorising andgrinding carob pods.
 5. A process according to claim 4, whereindeodorisation is carried out by treatment with an acid and strippingwith steam.
 6. A process according to claim 4, in which said particlesof adsorbent are sieved so that they have a grain size distribution of0.5 to 4 mm.
 7. A process according to claim 1, in which said aqueousextract is a coffee liquor containing from 1 to 50% by weight of solubleconstituents.
 8. A process according to claim 1, in which said aqueousextract is freed from volatile aromas by stripping with steam beforebeing contacted with said adsorbent and these volatile substances arerecombined with the extract after the treatment.
 9. A process accordingto claim 1, in which the volume of extract treated per unit of weight ofadsorbent is from 6 to
 80. 10. The article obtained by the process ofclaim 1.